Charged particle detectors that sense high energy charged particles are well known in the art and are used for a wide variety of applications, such as mass spectrometry, ion microscopy and night vision. One common charged particle detector includes a micro-channel plate (MCP) to intensify the number of charged particles (by generating secondary charged particles) and a florescent screen to detect the intensified charged particles. Another common charged particle detector includes a solid state active pixel sensor, which typically includes collector electrodes to collect incoming charged particles for a plurality of pixels. The pixel sensor detects the collected charged particles and integrates the charge. The signal charge is then read out by scanning pixels to generate a charged particle image.
A consequence of using high energy charged particles is the probability that some of the charged particles may be backscattered upon impact with the surface of the detector. The backscattered particles may produce a loss in signal and in spatial resolution. For solid state active pixel sensors, the collector electrodes are typically electrically isolated from each other, such as by a dielectric material. A consequence of the electrical isolation is that any dielectric material exposed between the collector electrodes may collect charge during bombardment of the charged particles and create crosstalk between the pixels. Another consequence of the electrical isolation is that the fill factor of the solid state pixel sensor (i.e., the ratio of the total charged particle collection surface area to the total contiguous area occupied by the pixel array) may be reduced, typically to be less than about 90%.